My husband is about to go nuts with his "baby", 89 Toyo p/u, 2 wheel drive, auto trans, 3spd with overdrive...transmission will not stay in overdrive, well actually he has to keep manually turning the overdrive off as it will not run. Any ideas on where to start?? None of this started until he replaced water pump and thermostat, now this...WOW!!! We are out of work and dont have a lot of $$$ to spend, but need our only source of transportation. Thanks for any suggestions you may offer....

Are there any lights lit on the dash ? check engine , overdrive etc..
could be just a shift solenoid ... Try draining trans fluid an replacing filter. Have to drop transmission pan .. what's the fluid look like ? a nice pink color ? does it smell burnt ? Is it full ?

Do you mean upshifting starts way early? Going from 2nd to 3rd in other words?
Ireally don't know your transmission,but the alternator problem might've possibly spiked and hurt your shifting solenoids in the ******. don-ohio (:^)

I doubt it's a transmission problem, it's more likely to be a wheel bearing issue, get another opinion at another shop or the toyota dealer.

Transmission Types : Ford E4OD/4R100, 4 Speed, Automatic Transmission
Comments: w/ Shallow Pan = 20 bolt holes 4 speed

Drive Trains : Four Wheel Drive
Transmission Types : Ford C6, 3 Speed, Automatic Transmission =17 bolts 3speed

What does the dash indicator say and does the stick have an od button on it? there is only 1 3 speed for the 460 and only 1 4speed for the 460

Engines:{300, 302, 351w}, {400, 351m, 460}, {6.9L, 7.3L IDI}, {352, 360, 390, ect.}
Fluid:
Pre '77: Type F
Post '77: Mercon
Display: PRND21
Pan 17 bolts "Utah" shape
Ratios:
1st 2.46:1
2nd 1.46:1
3rd 1.00:1
Trans code: K

so you should have the 3 speed acording to the code
http://broncozone.com/topic/10386-transmission-id-chart/

You did not say what model vehicle, but if it is a front-wheel drive with an overdrive transmission, and it takes off and stays in 2nd, then the computer has shut off power to the trans. You need to have it scanned to determine why the computer shut off the trans.

http://ezinearticles.com/?Find-the-Free-Auto-Repair-Manual-You-Need-Online&id=92717

I worked at Dealership which sold these things new. The transmission is notoriously weak...have a transmission shop you trust check it out. I have rebuilt a few of those transmissions,and overdrive is usually the first thing to let go.Don't drive it for long:the contamination running thru the trans.will cause more damage,add to the repair and leave you stranded somewhere.Sorry but I don't think you are getting away cheaplyThe Honda Passport is a Rodeo with a Honda grille.you can still buy some Isuzu mechanical stuff thru Honda stores.Good luck

High to low /low to high ratio, you will need to be stopped and the transmission in neutral for this to be changed.
The 2wd - Auto - Lock switch can be switched at any time, as it operates an electromagnetic clutch - 2wd is rear wheels driving only - Auto - is to automatically engage 4wd when wheel slippage is detected (this also happens when turning at intersections, due to the inside wheels having a shorter path to the outside wheels, and can give a binding effect on sealed roads (I don't drive with it in auto on sealed roads) auto is excellent if you get, or expect wheel spin from an intersection when wet, just flick it on before or when you have wheel spin, also on gravel roads, having it on auto will greatly reduce the sliding of the back end, and make the car noticeably more stable.
Lock - this locks the differential, which further reduces wheel spin, when in mud / snow, but this will also make the car not want to turn corners, due to it resisting the different distances traveled by the inside and outside wheels.
A/T switch - this actually has 3 positions, and changes the shifting points of the automatic transmission - the middle is normal - Hold is to hold the gear longer, to improve fuel economy, and not change down (kick down) as quickly - Power has the opposite effect, it makes the transmission change down sooner under acceleration.
Also the O/D (overdrive) button on the side of the Tee shift lever, is to engage / disengage overdrive (5th gear) - never do heavy towing in overdrive, this will cook the transmission and overheat the engine (due to the radiator being used as a heat exchanger for the transmission fluid.
Another little quirk - if the transmission light starts flashing every 40 to 50 km, this can indicate that the wheels are different diameters (a flat tyre, or tyres have been swapped around and the spare is more or less worn than the other tyres), the computer will pickup that the wheels are turning at different speeds.
When cold, it is normal for the transmission to stay in 3rd (2-3 minutes of driving), until it has warmed up, and then stay in 4th for a few more km's (5-6 minutes), before it has warmed up enough to change into 5th (overdrive).

No, the transmissions are probably a different length.

My experience has been they are not interchangeable - a number of sensors are usually unique to the specific cluster type installed.